Problem: Simplify the following expression: $t = \dfrac{8q}{5} - \dfrac{q}{8}$
Answer: In order to subtract expressions, they must have a common denominator. The smallest common denominator is the least common multiple of $5$ and $8$ $\lcm(5, 8) = 40$ $ t = \dfrac{8}{8} \cdot \dfrac{8q}{5} - \dfrac{5}{5} \cdot \dfrac{q}{8} $ $t = \dfrac{64q}{40} - \dfrac{5q}{40}$ $t = \dfrac{64q -5q}{40}$ $t = \dfrac{59q}{40}$